Short-circuit protection of battery cells using fuses

ABSTRACT

Apparatus, systems, and methods described herein relate to safety devices for electrochemical cells comprising an electrode tab electrically coupled to an electrode, the electrode including an electrode material disposed on a current collector. In some embodiments, a fuse can be operably coupled to or formed in the electrode tab. In some embodiments, the fuse can be formed by removing a portion of the electrode tab. In some embodiments, the fuse can include a thin strip of electrically resistive material configured to electrically couple multiple electrodes. In some embodiments, the current collector can include a metal-coated deformable mesh material such that the current collector is self-fusing. In some embodiments, the fuse can be configured to deform, break, melt, or otherwise discontinue electrical communication between the electrode and other components of the electrochemical cell in response to a high current condition, a high voltage condition, or a high temperature condition.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to, and the benefit of U.S. ProvisionalApplication No. 62/546,671 filed on Aug. 17, 2017, entitled“Overcharging Protection of Battery Cells Using Fuses,” the contents ofwhich are incorporated herein by reference in their entirety.

BACKGROUND

Current interrupt devices (CIDs) in existing Li-ion cells are generallytriggered by excessive gas generation within the Li-ion cells. To thisend, a small headspace around the jellyroll is usually included inexisting Li-ion cells. Once a cells begins to overcharge, excessive gasgenerated from overcharge can trigger a bi-stable metallic disk so as todisconnect one of the terminals. In some cases, gassing agents can beadded to the cell to generate extra gas in an overcharge state, such asadding Li₂CO₃ to the positive electrode. However, these gassing agentscan also introduce unwanted reactions within the cell, therebyincreasing the resistance and decreasing the coulombic efficiency of thecell.

An alternative method is to use a bi-stable metallic strip to cause anexternal short circuit in the presence of excessive gas generation dueto overcharge. This approach also relies on gas generation from thestorage electrodes and therefore can impose similar tradeoffs betweensafety and cell performance.

CIDs using the above approaches also suffer from accidental triggers. Ingeneral, operations of these devices are more dependent on thetemperature and pressure of the cell than on the cell voltage. However,the amount of gas generated by the storage electrodes can changesignificantly over the lifetime of a cell. At a safe cell voltage, anolder cell may generate much more gas than a newer cell does. Therefore,CIDs based on internal cell pressure can cause an unsafe condition eventhough the cell is operating safely.

SUMMARY

Apparatus, systems, and methods described herein relate to safetydevices for electrochemical cells comprising an electrode tabelectrically coupled to an electrode, the electrode including anelectrode material disposed on a current collector. In some embodiments,a fuse can be operably coupled to or formed in the electrode tab. Insome embodiments, the fuse can be formed by removing a portion of theelectrode tab. In some embodiments, the fuse can include a thin strip ofelectrically resistive material configured to electrically couplemultiple electrodes. In some embodiments, the current collector caninclude a metal-coated deformable mesh material such that the currentcollector is self-fusing. In some embodiments, the fuse can beconfigured to deform, break, melt, or otherwise discontinue electricalcommunication between the electrode and other components of theelectrochemical cell in response to a high current condition, a highvoltage condition, or a high temperature condition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1B shows a schematic of a battery system including a fuse toprotect the battery cell from overcharging, according to embodiments.

FIG. 2A shows a schematic of a device to manufacture the fuse shown inFIGS. 1A-1B, according to an embodiment.

FIGS. 2B-2D illustrate a method of manufacturing the fuse as shown inFIGS. 1A-1B, according to embodiments.

FIG. 3 shows a top view of an electrode tab including a holed regionthat can be used as a fuse for overcharge protection, according to anembodiment.

FIG. 4 shows a top view of electrode tabs, according to embodiments.

FIG. 5 illustrates a method for manufacturing an electrode, according toan embodiment.

FIG. 6 shows a top view of an electrode manufactured according to themethod of FIG. 5.

FIG. 7 illustrates a method for manufacturing an electrode, according toan embodiment.

FIGS. 8A-8D show perspective views of an electrode at each stage of themethod of FIG. 7.

DETAILED DESCRIPTION

Embodiments described herein relate generally to protection of batterycells from overcharging using current interrupt devices. In someembodiments, a battery system includes a battery cell that includes acathode and an anode, a cathode tab electrically coupled to the cathode,and an anode tab electrically coupled to the anode. An interrupt device,such as a fuse, is operably coupled to at least one of the cathode tabor the anode tab or formed in at least one of the cathode tab and/or theanode tab. Upon overcharging of the battery cell, the voltage betweenthe cathode tab and the anode tab causes the fuse to disconnect at leastone of the cathode tab or the anode tab, thereby protecting the batterycell from further damage.

As used herein, the term “semi-solid” refers to a material that is amixture of liquid and solid phases, for example, such as a particlesuspension, colloidal suspension, emulsion, gel, slurry or micelle.

As used herein, the terms “condensed ion-storing liquid” or “condensedliquid” refers to a liquid that is not merely a solvent, as in the caseof an aqueous flow cell catholyte or analyte, but rather, that is itselfredox-active. Of course, such a liquid form may also be diluted by ormixed with another, non-redox-active liquid that is a diluent orsolvent, including mixing with such a diluent to form a lower-meltingliquid phase, emulsion or micelles including the ion-storing liquid.

As used in this specification, the terms “about” and “approximately”generally include plus or minus 10% of the value stated. For example,about 5 would include 4.5 to 5.5, approximately 10 would include 9 to11, and about 100 would include 90 to 110.

As used herein, the terms “activated carbon network” and “networkedcarbon” relate to a general qualitative state of an electrode. Forexample, an electrode with an activated carbon network (or networkedcarbon) is such that the carbon particles within the electrode assume anindividual particle morphology and arrangement with respect to eachother that facilitates electrical contact and electrical conductivitybetween particles. Conversely, the terms “unactivated carbon network”and “unnetworked carbon” relate to an electrode wherein the carbonparticles either exist as individual particle islands or multi-particleagglomerate islands that may not be sufficiently connected to provideadequate electrical conduction through the electrode.

The Battery Cell

In some embodiments, the electrochemical cell includes a cathode (alsoreferred to as a cathode material) disposed on a cathode currentcollector, an anode (also referred to as an anode material) disposed onan anode current collector, and an ion-permeable membrane (alsodescribed herein as a “separator”) disposed in between. The assembly ofthe cathode, the cathode current collector, the anode, the anode currentcollector, and the separator is contained substantially in a batteryenclosure, for example, a pouch. Any cathode tab can be electricallyconnected to the cathode current collector and extends beyond the pouchfor connection with external circuit. Similarly, any anode tab can beelectrically connected to the anode current collector and extends beyondthe pouch for connection with external circuit.

In some embodiments, the cathode material can include, for example,Nickel Cobalt Aluminum (NCA), Core Shell Gradient (CSG), Spinel LithiumManganese Oxide (LMO), High Voltage Spinel (LNMO), Lithium IronPhosphate (LFP), Lithium Cobalt Oxide (LCO), and Nickel Cobalt Manganese(NCM), among others.

The anode material can be selected from a variety of materials. In someembodiments, the anode material comprises a carbon-based material,including, but not limited to, graphite, hard carbon, carbon nanotubes,carbon nanofibers, porous carbon, and graphene. In some embodiments, theanode material comprises a titanium-based oxide including, but are notlimited to, spinel Li₄Ti₅O₁₂ (LTO) and titanium dioxide (TiO₂, Titania).In some embodiments, the anode material comprises alloy or de-alloymaterial including, but not limited to, silicon, silicon monoxide (SiO),germanium, tin, and tin oxide (SnO₂). In some embodiments, the anodematerial comprises a transition metal compound (e.g., oxides,phosphides, sulphides and nitrides). The general formula of a transitionmetal compound can be written as M_(x)N_(y), where M can be selectedfrom iron (Fe), cobalt (Co), copper (Cu), manganese (Mn), and nickel(Ni), and N can be selected from oxygen (O), phosphorous (P), sulfur(S), and nitrogen (N).

In some embodiments, the anode material comprises an intermetalliccompound. An intermetallic compound can be based on a formulation MM′,wherein M is one metal element and M′ is a different metal element. Anintermetallic compound can also include more than two metal elements.The M atoms of an intermetallic compound can be, for example, Cu, Li,and Mn, and the M′ element of an intermetallic compound can be, forexample, Sb. Exemplary intermetallic compounds include Cu₂Sb, Li₂CuSb,and Li₃Sb, among others. In one example, the intermetallic compound inthe anode material can have fully disordered structures in which the Mor M′ atoms are arranged in a random manner. In another example, theintermetallic compound in the anode material has partially disorderedstructures in which the M or M′ atoms in the crystal lattice arearranged in a non-random manner.

In some embodiments, the anode material can be porous so as to increasethe surface area and enhance the rate of lithium intercalation in theresulting electrodes. In one example, the anode material includes porousMn₂O₃, which can be prepared by, for example, thermal decomposition ofMnCO₃ microspheres. In another example, the anode material includesporous carbon fibers prepared by, for example, electrospinning a blendsolution of polyacrylonitrile and poly(l-lactide), followed bycarbonization. In some embodiments, the porosity of the anode materialcan be achieved or increased by using a porous current collector. Forexample, the anode material can include Cu₂Sb, which is depositedconformally on a porous foam structure, to have certain degree ofporosity.

In some embodiments, at least one of the anode material or the cathodematerial can include a semi-solid or a condensed ion-storing liquidreactant. By “semi-solid” it is meant that the material is a mixture ofliquid and solid phases, for example, such as a semi-solid, particlesuspension, colloidal suspension, emulsion, gel, slurry or micelle.“Condensed ion-storing liquid” or “condensed liquid” means that theliquid is not merely a solvent as it is in the case of an aqueous flowcell catholyte or anolyte, but rather, that the liquid is itselfredox-active. Such a liquid form may also be diluted by or mixed withanother, non-redox-active liquid that is a diluent or solvent, includingmixing with such a diluent to form a lower-melting liquid phase,emulsion or micelles including the ion-storing liquid. In someembodiments, semi-solid electrode compositions (also referred to hereinas “semi-solid suspension” and/or “slurry”) can include a suspension ofelectrochemically-active agents (anode particulates and/or cathodeparticulates) and, optionally, electronically conductive particles. Thecathodic particles and conductive particles are co-suspended in anelectrolyte to produce a cathode semi-solid. The anodic particles andconductive particles are co-suspended in an electrolyte to produce ananode semi-solid. The semi-solids are capable of flowing due to anapplied pressure, gravitational force, or other imposed field thatexerts a force on the semi-solid, and optionally, with the aid ofmechanical vibration. Examples of batteries utilizing semi-solidsuspensions are described in U.S. Pat. No. 9,362,583, entitled“Semi-Solid Electrodes Having High Rate Capability,” the entiredisclosure of which is hereby incorporated by reference.

In some embodiments, an electrochemical cell includes an anode, and asemi-solid cathode. The semi-solid cathode includes a suspension ofabout 35% to about 75% by volume of an active material and about 0.5% toabout 8% by volume of a conductive material in a non-aqueous liquidelectrolyte. In some embodiments, the ion-permeable membrane (alsodescribed herein as the “separator”) can be disposed between the anodeand the semi-solid cathode. In some embodiments, the semi-solid cathodecan have a thickness in the range of about 50 μm to about 3,000 μm,about 100 μm to about 2,500 μm, about 150 μm to about 2,000 μm, about200 μm to about 1,500 μm, about 250 μm to about 1,000 μm, about 50 μm toabout 2,500 μm, about 50 μm to about 2,000 μm, about 50 μm to about1,500 μm, about 50 μm to about 1,000 μm, about 100 μm to about 3,000 μm,about 150 μm to about 3,000 μm, about 200 μm to about 3,000 μm, about250 μm to about 3,000 μm, greater than about 50 μm, greater than about100 μm, greater than about 150 μm, greater than about 200 μm, greaterthan about 250 μm, less than about 3,000 μm, less than about 2,500 μm,less than about 2,000 μm, less than about 1,500 μm, or less than about1,000 μm, inclusive of all values and ranges therebetween. In someembodiments, the electrochemical cell can have an area specific capacityof at least about 5 mAh/cm² at a C-rate of C/4, at least about 6_mAh/cm²at a C-rate of C/4, at least about 7 mAh/cm² at a C-rate of C/4, atleast about 8_mAh/cm² at a C-rate of C/4, at least about 9 mAh/cm² at aC-rate of C/4, at least about 10_mAh/cm² at a C-rate of C/4, at leastabout 11 mAh/cm² at a C-rate of C/4, or at least about 12_mAh/cm² at aC-rate of C/4, inclusive of all values and ranges therebetween. In someembodiments, the semi-solid cathode suspension can have an electronicconductivity of at least about 10⁻⁸ S/cm, at least about 10⁻⁷ S/cm, atleast about 10⁻⁶ S/cm, at least about 10⁻⁵ S/cm, at least about 10⁻⁴S/cm, at least about 10⁻³ S/cm, at least about 10⁻² S/cm, or at leastabout 10⁻¹ S/cm, inclusive of all values and ranges therebetween. Insome embodiments, the semi-solid cathode suspension can have a mixingindex of at least about 0.7, at least about 0.8, at least about 0.9, atleast about 0.91, at least about 0.92, at least about 0.93, at leastabout 0.94, at least about 0.95, at least about 0.96, at least about0.97, at least about 0.98, or at least about 0.99, inclusive of allvalues and ranges therebetween.

In some embodiments, an electrochemical cell includes a semi-solid anodeand a semi-solid cathode. The semi-solid anode includes a suspension ofabout 35% to about 75% by volume of a first active material and about 0%to about 10% by volume of a first conductive material in a firstnon-aqueous liquid electrolyte. The semi-solid cathode includes asuspension of about 35% to about 75% by volume of a second activematerial, and about 0.5% to about 8% by volume of a second conductivematerial in a second non-aqueous liquid electrolyte. In someembodiments, the ion-permeable membrane is disposed between thesemi-solid anode and the semi-solid cathode. Each of the semi-solidanode and the semi-solid cathode have a thickness of about 250 μm toabout 2,000 μm and the electrochemical cell has an area specificcapacity of at least about 7 mAh/cm² at a C-rate of C/4. In someembodiments, the first conductive material included in the semi-solidanode is about 0.5% to about 2% by volume. In some embodiments, thesecond active material included in the semi-solid cathode is about 50%to about 75% by volume.

In some embodiments, an electrochemical cell includes an anode and asemi-solid cathode. The semi-solid cathode includes a suspension ofabout 35% to about 75% by volume of an active material and about 0.5% toabout 8% by volume of a conductive material in a non-aqueous liquidelectrolyte. In some embodiments, the ion-permeable membrane is disposedbetween the anode and semi-solid cathode. The semi-solid cathode has athickness in the range of about 250 μm to about 2,000 μm, and theelectrochemical cell has an area specific capacity of at least about 7mAh/cm² at a C-rate of C/2. In some embodiments, the semi-solid cathodesuspension has a mixing index of at least about 0.9.

In some embodiments, an electrochemical cell includes a semi-solid anodeand a semi-solid cathode. The semi-solid anode includes a suspension ofabout 35% to about 75% by volume of a first active material and about 0%to about 10% by volume of a first conductive material in a firstnon-aqueous liquid electrolyte. The semi-solid cathode includes asuspension of about 35% to about 75% by volume of a second activematerial, and about 0.5% to about 8% by volume of a second conductivematerial in a second non-aqueous liquid electrolyte. In someembodiments, the ion-permeable membrane is disposed between thesemi-solid anode and the semi-solid cathode. Each of the semi-solidanode and the semi-solid cathode have a thickness of about 250 μm toabout 2,000 μm and the electrochemical cell has an area specificcapacity of at least about 7 mAh/cm² at a C-rate of C/2. In someembodiments, the first conductive material included in the semi-solidanode is about 0.5% to about 2% by volume. In some embodiments, thesecond active material included in the semi-solid cathode is about 50%to about 75% by volume.

In some embodiments, the electrode materials described herein can be aflowable semi-solid or condensed liquid composition. A flowablesemi-solid electrode can include a suspension of an electrochemicallyactive material (anodic or cathodic particles or particulates), andoptionally an electronically conductive material (e.g., carbon) in anon-aqueous liquid electrolyte. Said another way, the active electrodeparticles and conductive particles are co-suspended in an electrolyte toproduce a semi-solid electrode. Examples of battery architecturesutilizing semi-solid suspensions are described in International PatentPublication No. WO 2012/024499, entitled “Stationary, Fluid RedoxElectrode,” and International Patent Publication No. WO 2012/088442,entitled “Semi-Solid Filled Battery and Method of Manufacture,” theentire disclosures of which are hereby incorporated by reference.

In some embodiments, semi-solid electrode compositions (also referred toherein as “semi-solid suspension” and/or “slurry”) described herein canbe mixed in a batch process e.g., with a batch mixer that can include,e.g., a high shear mixture, a planetary mixture, a centrifugal planetarymixture, a sigma mixture, a CAM mixture, and/or a roller mixture, with aspecific spatial and/or temporal ordering of component addition, asdescribed in more detail herein. In some embodiments, slurry componentscan be mixed in a continuous process (e.g. in an extruder), with aspecific spatial and/or temporal ordering of component addition.

The mixing and forming of a semi-solid electrode generally includes: (i)raw material conveyance and/or feeding, (ii) mixing, (iii) mixed slurryconveyance, (iv) dispensing and/or extruding, and (v) forming. In someembodiments, multiple steps in the process can be performed at the sametime and/or with the same piece of equipment. For example, the mixingand conveyance of the slurry can be performed at the same time with anextruder. Each step in the process can include one or more possibleembodiments. For example, each step in the process can be performedmanually or by any of a variety of process equipment. Each step can alsoinclude one or more sub-processes and, optionally, an inspection step tomonitor process quality.

In some embodiments, the process conditions can be selected to produce aprepared slurry having a mixing index of at least about 0.80, at leastabout 0.90, at least about 0.95, or at least about 0.975. In someembodiments, the process conditions can be selected to produce aprepared slurry having an electronic conductivity of at least about10'S/cm, at least about 10⁻⁵ S/cm, at least about 10⁻⁴ S/cm, at leastabout 10⁻³ S/cm, or at least about 10⁻² S/cm. In some embodiments, theprocess conditions can be selected to produce a prepared slurry havingan apparent viscosity at room temperature of less than about 100,000Pa-s, less than about 10,000 Pa-s, or less than about 1,000 Pa-s, all atan apparent shear rate of 1,000 s⁻¹. In some embodiments, the processconditions can be selected to produce a prepared slurry having two ormore properties as described herein. Examples of systems and methodsthat can be used for preparing the semi-solid compositions and/orelectrodes are described in U.S. patent application Ser. No. 13/832,861,filed Mar. 15, 2013, entitled “Electrochemical Slurry Compositions andMethods for Preparing the Same,” the entire disclosure of which ishereby incorporated by reference.

In some embodiments, one of both of the current collectors can include aconductive substrate. In one example, the conductive substrate comprisesa metal material such as aluminum, copper, lithium, nickel, stainlesssteel, tantalum, titanium, tungsten, vanadium, or their combinations oralloys. In another example, the conductive substrate comprises anon-metal material such as carbon, carbon nanotubes, or a metal oxide ortheir combinations of composite (e.g., TiN, TiB₂, MoSi₂, n-BaTiO₃,Ti2O₃, ReO₃, RuO₂, IrO₂, etc.).

In some embodiments, one or both of the current collectors can include abase substrate having one or more surface coatings so as to improve themechanical, thermal, chemical, or electrical properties of the currentcollector. In one example, the coating(s) on the current collector canbe configured to reduce corrosion and alter adhesion characteristics(e.g., hydrophilic or hydrophobic coatings, respectively). In anotherexample, the coating(s) on the current collector can comprise a materialof high electrical conductivity to improve the overall charge transportof the base substrate. In yet another example, the coatings can comprisea material of high thermal conductivity to facilitate heat dissipationof the base substrate and protect the battery from overheating. In yetanother example, the coatings can comprise a heat-resistant orfire-retardant material to prevent the battery from fire hazards. In yetanother example, the coatings can be configured to be rough so as toincrease the surface area and/or the adhesion with the anode material.In yet another example, the coatings can include a material with goodadhering or gluing properties with the anode material.

In some embodiments, one or both of the current collectors can include aconductive substrate having a roughened surface so as to improve themechanical, electrical, and thermal contact between the anode materialand the current collector. The roughened surface of the currentcollector can increase the physical contact area between the anodematerial and the current collector, thereby increasing the adherence ofthe anode material to the current collector. The increased physicalcontact area can also improve the electrical and thermal contact (e.g.,reduced electrical and thermal resistance) between the current collectorand the anode material.

In some embodiments, one or both of the current collectors can include aporous current collector such as a wire mesh. The wire mesh (alsoreferred to herein as mesh) can include any number of filament wiresthat can be assembled in various configurations using suitableprocesses, such as a regular pattern or structure produced by weaving,braiding, knitting, etc. or a more random pattern or structure producedby randomly distributing wires and joining them by welding, adhesives,or other suitable techniques. Moreover, the wires comprising the meshcan be any suitable material. For example, in some embodiments, thewires are metallic such as, steel, aluminum, copper, titanium or anyother suitable metal. In other embodiments, the wires can be aconductive non-metallic material such as, for example, carbon nanofiberor any other suitable material. In some embodiments, the wires caninclude coatings. For example, the coatings can be configured to reducecorrosion and enhance or reduce adhesion characteristics (e.g.,hydrophilic or hydrophobic coatings, respectively). Examples of porouscurrent collectors are described in U.S. Patent Publication No. U.S.2013/0065122 A1, entitled “Semi-Solid Electrode Cell Having A PorousCurrent Collector and Methods of Manufacture,” the entire disclosures ofwhich is hereby incorporated by reference.

In some embodiments, the separator can be a thin, microporous membranethat electrically separates the anode from the cathode but allows ionsto pass through the pores between the two electrolytes duringdischarging and charging. In some embodiments, the separator includes athermoplastic polymer, such as polyolefins, polyvinyl chlorides, nylons,fluorocarbons, and polystyrenes, among others. In some embodiments, theseparator includes polyolefins material that comprises, for example,polyethylene, ultra-high molecular weight polyethylene, polypropylene,polybutene, polymethylpentene, polyisoprene, copolymers thereof, andtheir combinations. Exemplary combinations can include, but are notlimited to, mixtures containing two or more of the followingpolyethylene, ultra-high molecular weight polyethylene, andpolypropylene, as well as, mixtures of the foregoing with copolymerssuch as ethylene-butene copolymer and ethylene-hexene copolymer.

In some embodiments, the separator can include thermosetting plastics,such as polyimide (PI), poly amide (PA), and poly amide imide (PAI),among others. In some embodiments, the separator can include a non-woventype separator. In some embodiments, the non-woven type separator can bemade of ceramic fibers. In some embodiments, the non-woven typeseparator can be made of fibrillated fibers. In some embodiments, thenon-woven type separator can be made of cellulose nanofibers.

The pouch in the electrochemical cell substantially contains thecathode, the cathode current collector, the anode, the anode currentcollector, and the separator. The pouch can physically separate theelectrochemical cell from adjacent cells so as to mitigate or eliminatedefect propagation, and to facilitate easy handling of theelectrochemical cell during battery manufacturing. The pouch can alsoreduce the possibility of fire ignition of flammable electrolyte duringpossible welding processes in battery manufacturing, which at timesgenerates sparks, when working with a semi-solid electrode.

In some embodiments, the cathode, the cathode current collector, theanode, the anode current collector, and the separator are sealed in thepouch (e.g., via vacuum sealing). In these embodiments, the pouch canstill reduce or eliminate chances of exposure to sparking (e.g., fromwelding processes) that could ignite the electrolyte. A final sealingstep can be carried out after the welding process to seal one or moresingle pouch battery cells into an external pouch or package, in whichcase the external pouch or package can function as moisture control.Examples of battery architectures utilizing single pouch battery cellsare described in U.S. patent application Ser. No. 15/185,625, entitled“Single Pouch Battery Cells and Methods of Manufacture,” the entiredisclosure of which is hereby incorporated by reference.

In some embodiments, the pouch includes a three-layer structure, namelyan intermediate layer sandwiched by an outer layer and an inner layer,wherein the inner layer is in contact with the electrodes and theelectrolyte. For example, the outer layer can include a nylon-basedpolymer film. The inner layer can include a polypropylene (PP) polymerfilm, which can be corrosion-resistive to acids or other electrolyte andinsoluble in electrolyte solvents. The intermediate layer can include ofaluminum (Al) foil. This structure allows the pouch to have both highmechanical flexibility and strength.

In some embodiments, the outer layer of the pouch includes polymermaterials such as polyethylene terephthalate (PET), polybutyleneterephthalate (PBT), nylon, high-density polyethylene (HDPE), orientedpolypropylene (o-PP), polyvinyl chloride (PVC), polyimide (PI),polysulfone (PSU), and their combinations.

In some embodiments, the intermediate layer of the pouch includes metallayers (foils, substrates, films, etc.) comprising aluminum (Al), copper(Cu), stainless steel (SUS), and their alloys or combinations.

In some embodiments, the inner layer of the pouch includes materialssuch as cast polypropylene (c-PP), polyethylene (PE), ethylenevinylacetate (EVA), and their combinations.

In some embodiments, the pouch includes a two-layer structure, namely anouter layer and an inner layer. In some embodiments, the outer layer caninclude PET, PBT, or other materials as described above. In someembodiments, the inner layer can include PP, PE, or other materialsdescribed above.

In some embodiments, the pouch can include a water barrier layer and/orgas barrier layer. In some embodiments, the barrier layer can include ametal layer and/or an oxide layer. In some embodiments, it can bebeneficial to include the oxide layer because oxide layers tend to beinsulating and can prevent short circuits within the battery.

In some embodiments, there can be only one (or two) unit cell(s)assembly within the pouch, the pouch can be substantially thinner thanpouches commonly used for multi-stack battery cells. For example, thepouch can have a thickness less than about 500 μm, less than about 450μm, less than about 400 μm, less than about 350 μm, less than about 300μm, less than about 250 μm, less than about 200 μm, less than about 150μm, less than about 100 μm, less than about 50 μm, less than about 45μm, less than about 40 μm, less than about 35 μm, less than about 30 μm,less than about 29 μm, less than about 28 μm, less than about 27 μm,less than about 26 μm, less than about 25 μm, less than about 24 μm,less than about 23 μm, less than about 22 μm, less than about 21 μm,less than about 20 μm, less than about 19 μm, less than about 18 μm,less than about 17 μm, less than about 16 μm, less than about 15 μm,less than about 14 μm, less than about 13 μm, less than about 12 μm,less than about 11 μm, less than about 10 μm, less than about 9 μm, lessthan about 8 μm, less than about 7 μm, less than about 6 μm, or lessthan about 5 μm, inclusive of all values and ranges therebetween. Thethickness of the pouch as used here can be defined as the thickness ofthe film that forms the pouch. In some embodiments, the pouch can be alaminate film, a single-ply film, a two-ply film, a three-ply film, or afilm having greater than three ply. In some embodiments, the pouch caninclude more than one piece of film coupled together, for instance two,three, four, five, or greater than five pieces of film.

In some embodiments, the thickness of the pouch can depend on at leasttwo aspects. In one aspect, it can be desirable to achieve high energydensity in the resulting battery cells, in which case thinner pouchescan be helpful since a larger portion of space within a battery cell canbe reserved for electrode materials. In another aspect, it can bedesirable to maintain or improve the safety advantage of the pouch. Inthis case, a thicker pouch can be helpful to, for example, reduce firehazard. In some embodiments, the pouch thickness can be quantified as aratio of the volume occupied by the pouch material to the total volumeof the battery cell. In some embodiments, the pouch thickness can beabout 5% to about 40% in terms of the ratio as defined above. In someembodiments, the pouch thickness can be about 10% to about 30% in termsof the ratio as defined above.

In some embodiments, the thickness of the electrochemical cell(including the thickness of the pouch and the thickness of theelectrodes) can be about 100 μm to about 3 mm, about 150 μm to about 2.5mm, about 200 μm to about 2 mm, about 250 μm to about 1.5 mm, about 300μm to about 1 mm, about 100 μm to about 2.5 mm, about 100 μm to about 2mm, about 100 μm to about 1.5 mm, about 100 μm to about 1 mm, about 150μm to about 3 mm, about 200 μm to about 3 mm, about 250 μm to about 3mm, about 300 μm to about 3 mm, about 500 μm to about 3 mm, about 750 μmto about 3 mm, about 1 mm to about 3 mm, or about 2 mm to about 3 mm,inclusive of all values and ranges therebetween. In some embodiments,the thickness of the electrochemical cell (including the thickness ofthe pouch and the thickness of the electrodes) can be greater than about100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 400 μm, 500 μm, 750 μm, 1 mm, 2mm, or 3 mm, inclusive of all values and ranges therebetween. In someembodiments, the thickness of the electrochemical cell (including thethickness of the pouch and the thickness of the electrodes) can be lessthan about 3 mm, 2 mm, 1 mm, 750 μm, 500 μm, 400 μm, 300 μm, 250 μm, 200μm, 150 μm, or 100 μm, inclusive of all values and ranges therebetween.

In some embodiments, the pouch includes a single layer of lower costmaterials that are thinner. For example, these materials can bepolypropylene or a combination of polyolefins that can be sealedtogether using heat or pressure (e.g., thermal fusion or vacuumsealing).

In some embodiments, the pouch includes a single layer of fire retardantmaterials so as to prevent the propagation of fire hazard from onesingle pouch battery cell to another. In some embodiments, the pouchincludes an air-proof material so as to prevent the propagation of gasreleased by one single pouch battery cell to another, thereby reducingdefect propagation.

In some embodiments, overcharging protection of battery systems usingcurrent interrupt devices can alternatively or additionally includefuses, e.g., for overcharging protection. A fuse can be any electricalsafety device that operates in any fashion to protect theelectrochemical cell from overcharging. Embodiments of the fuse-basedcurrent interrupt device include any fuse device and configuration.Embodiments of the fuse-based current interrupt device can be active orpassive. Embodiments of the fuse-based current interrupt device can besacrificial or non-sacrificial. Embodiments of the fuse-based currentinterrupt device can include any fuse described herein and any otherfuse known in the art at the time of filing individually or inconjunction with any temperature-based, gas-based, pressure-based, orother current interrupt device known in the art at the time of filing.

In some embodiments, an electrochemical cell can include a cathode tabelectrically coupled to a cathode and an anode tab electrically coupledto an anode, the anode separated from the cathode by an ion-permeablemembrane. In some embodiments, at least one of the cathode tab and theanode tab can include a fuse configured to discontinue electricalcommunication through the at least one of the cathode tab and the anodetab. In some embodiments, the fuse can be formed by removing a portionof at least one of the cathode tab and the anode tab. In someembodiments, the fuse can be configured to discontinue communication ofelectrical current through the at least one of the cathode tab and theanode tab in response to a voltage reaching or exceeding a voltagethreshold. In some embodiments, the fuse can include a plurality ofthinned portions configured to break when a current being communicatedthrough the fuse reaches or exceeds a current threshold. In someembodiments, the electrochemical cell can include a pouch materialdimensioned and configured to contain the cathode, the anode, and theion-permeable membrane. In some embodiments, the fuse is disposed withinthe pouch material. In some embodiments, the fuse can be manufactured byremoving a plurality of portions of at least one of the anode tab andthe cathode tab. In some embodiments, removing the plurality of portionsof at least one of the anode tab and the cathode tab defines a pluralityof apertures through at least one of the anode tab and the cathode tab.In some embodiments, a first aperture of the plurality of apertures canbe positioned between about 100 μm and about 20 mm from a first edge ofat least one of the anode tab and the cathode tab, and a second apertureof the plurality of apertures can be positioned between about 100 μm andabout 20 mm from a second edge of at least one of the anode tab and thecathode tab, the second edge opposite the first edge. In someembodiments, the position of the first aperture and the second apertureforms a first bridge and a second bridge, respectively, through whichcurrent is communicated during normal operation of the electrochemicalcell. In some embodiments, the fuse can be configured such that it willnot break until a voltage of a current communicated through the fusereaches or exceeds a voltage threshold. In some embodiments, the fusecan be configured such that it will not break until a current level of acurrent communicated through the fuse reaches or exceeds a currentthreshold.

In some embodiments, a method of manufacturing an electrode for anelectrochemical cell can include disposing an electrode material onto acurrent collector, a portion of the current collector extending beyondthe electrode material to form an electrode tab, and removing a portionof the electrode tab to form an aperture therethrough to form a fuse inthe electrode tab. In some embodiments, the fuse can be configured tobreak when a current level of an electrical current communicated throughthe fuse reaches or exceeds a predetermined current level. In someembodiments, the fuse can be configured to break when a voltage of anelectrical current communicated through the fuse reaches or exceeds apredetermined voltage. In some embodiments, the electrode tab caninclude a plurality of fuses configured to break when a current level ofan electrical current communicated through the thinned portion reachesor exceeds a predetermined current level. In some embodiments, theelectrode can be a cathode and the method can include disposing thecathode and an anode into a pouch with an ion-permeable membraneinterposed therebetween to form an electrochemical cell. In someembodiments, the pouch can be dimensioned and configured to contain thecathode, the anode, the ion-permeable membrane, and the fuse. In someembodiments, the removing step can include removing a plurality ofportions of the electrode tab to define a plurality of aperturestherethrough. In some embodiments, a first aperture of the plurality ofapertures can be positioned between about 100 μm and about 20 mm from afirst edge of the electrode tab, and a second aperture of the pluralityof apertures can be positioned between about 100 μm and about 20 mm froma second edge of the electrode tab, the second edge opposite the firstedge. In some embodiments, the position of the first aperture and thesecond aperture can form a first thinned portion and a second thinnedportion, respectively, through which current is communicated duringnormal operation of the electrochemical cell. In some embodiments, thefuse can be configured such that it will not break until a voltage of acurrent communicated through the fuse reaches or exceeds a voltagethreshold. In some embodiments, the fuse can be configured such that itwill not break until a current level of a current communicated throughthe fuse reaches or exceeds a current threshold.

In some embodiments, an electrochemical cell can include a cathodeincluding a cathode current collector and a cathode material disposed onthe cathode current collector, an anode including an anode currentcollector and an anode material disposed on the anode current collector,and an ion-permeable membrane interposed between the cathode and theanode. In some embodiments, at least one of the cathode currentcollector and the anode current collector can be configured to deformwhen a current level reaches or exceeds a predetermined currentthreshold. In some embodiments, at least one of the cathode and theanode can include a mesh comprising a polymer material. In someembodiments, the mesh can be spray-coated with a metal to form at leastone of the cathode current collector or the anode current collector. Insome embodiments, at least one of the cathode material and the anodematerial can include a semi-solid electrode material including an activematerial and a conductive material in a liquid electrolyte. In someembodiments, at least a portion of the porous current collector extendsbeyond the ion-permeable membrane to form at least one of a cathode taband an anode tab. In some embodiments, the cathode current collector canbe a first current collector of a plurality of current collectors, theplurality of current collectors electrically coupled together via aplurality of fuses. In some embodiments, the first current collector ofthe plurality of current collectors can include an electrode tab. Insome embodiments, the cathode material can includes a mixture of a solidactive material and a liquid electrolyte. In some embodiments, the anodecurrent collector can be a first current collector of a plurality ofcurrent collectors, the plurality of current collectors electricallycoupled together via a plurality of fuses. In some embodiments, thefirst current collector of the plurality of current collectors caninclude an electrode tab. In some embodiments, the anode material caninclude a mixture of a solid active material and a liquid electrolyte.

FIGS. 1A-1B show schematics of a battery system 100 including a fuse toprotect the battery cell 100 from overcharging. The battery system 100includes a battery cell 110 and a first tab 120 (e.g., a cathode tab)and a second tab 130 (e.g., an anode tab), collectively “the tabs 120and 130, to connect the battery cell 110 to external circuit forcharging and/or discharging. The battery cell 110 and part of the tabs120 and 130 are enclosed in a pouch 140. FIG. 1B shows a magnified viewof the first tab 120, which includes a narrowed region 125 defined bytwo elongated holes punched on the cathode tab 120. The narrowed region125 has a smaller width for electrical current compared to the rest ofthe first tab 120. As understood in the art, a smaller width of thefirst tab 120 can lead to a larger resistance, which in turn cangenerate more heat. The heat, in combination with the smaller width, cancause the narrowed region 125 to preferentially deform, break, melt, orotherwise discontinue electrical current through the first tab 120 whenthe electrical current is above a threshold value. In some embodiments,the fuse can be integrated into the second tab 130 also or instead. Inthis manner, the battery system 100 can be configured to automaticallydisconnect from external circuit upon overcharging or during anotherunwanted operating condition or electrochemical cell failure condition.

In some embodiments, the absolute width of the narrowed region 125 canbe about 100 μm to about 20 mm, about 500 μm to about 19 mm, about 750μm to about 18 mm, about 0.5 mm to about 17 mm, about 1 mm to about 16mm, about 1.5 mm to about 15 mm, about 2 mm to about 14 mm, about 3 mmto about 13 mm, about 4 mm to about 12 mm, about 5 mm to about 11 mm,about 6 mm to about 10 mm, about 7 mm to about 9 mm, about 0.5 mm toabout 20 mm, about 100 μm to about 19 mm, about 100 μm to about 18 μm,about 100 μm to about 17 mm, about 100 μm to about 16 mm, about 100 μmto about 15 mm, about 100 μm to about 14 mm, about 100 μm to about 13mm, about 100 μm to about 12 mm, about 100 μm to about 11 mm, about 100μm to about 10 mm, about 100 μm to about 9 mm, about 100 μm to about 8mm, about 100 μm to about 7 mm, about 100 μm to about 6 mm, about 100 μmto about 5 mm, about 100 μm to about 4 mm, about 100 μm to about 3 mm,about 100 μm to about 2 mm, about 100 μm to about 1 mm, about 100 μm toabout 750 μm, about 100 μm to about 500 μm, about 500 μm to about 20 mm,about 750 μm to about 20 mm, about 0.5 mm to about 20 mm, about 1 mm toabout 20 mm, about 2 mm to about 20 mm, about 3 mm to about 20 mm, about4 mm to about 20 mm, about 5 mm to about 20 mm, about 6 mm to about 20mm, about 7 mm to about 20 mm, about 8 mm to about 20 mm, about 9 mm toabout 20 mm, about 10 mm to about 20 mm, about 11 mm to about 20 mm,about 12 mm to about 20 mm, about 13 mm to about 20 mm, about 14 mm toabout 20 mm, about 15 mm to about 20 mm, about 16 mm to about 20 mm,about 17 mm to about 20 mm, about 18 mm to about 20 mm, or about 19 mmto about 20 mm, inclusive of all values and ranges therebetween. In someembodiments, the width of the narrowed region 125 can be greater thanabout 100 μm, about 500 μm, about 750 μm, about 0.5 mm, about 1 mm,about 2 mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 8 mm,about 9 mm, about 10 mm, about 11 mm, about 12 mm, about 13 mm, about 14mm, about 15 mm, about 16 mm, about 17 mm, about 18 mm, about 19 mm, orabout 20 mm, inclusive of all values and ranges therebetween. In someembodiments, the width of the narrowed region 125 can be less than about20 mm, about 19 mm, about 18 mm, about 17 mm, about 16 mm, about 15 mm,about 14 mm, about 13 mm, about 12 mm, about 11 mm, about 10 mm, about 9mm, about 8 mm, about 7 mm, about 6 mm, about 5 mm, about 4 mm, about 3mm, about 2 mm, about 1 mm, about 750 μm, about 500 μm, or about 100 μm,inclusive of all values and ranges therebetween.

In some embodiments, the ratio of the width of the narrowed region 125to the width of the first tab 120 can be about 1% to about 20% (e.g.,about 1%, about 2%, about 3%, about 4%, about 5%, about 7.5%, about 10%,about 12.5%, about 15%, about 17.5%, or about 20%, including any valuesand sub ranges in between).

In some embodiments, the second tab 130 can also include a narrowedregion to function as a fuse. In some embodiments, the battery system100 can include two fuses: one defined on the first tab 120 and theother defined on the second tab 130. In some embodiments, the first tab120 and/or the second tab 130 can include more than one narrowed regionto function as fuses. In some embodiments, a portion of the electrodetab material (e.g., for the first tab 120 or the second tab 130) can bethinned, stretched, stamped, etched, heat treated, or otherwiseconfigured to create a higher resistance path through the electrode tab.In some embodiments, a portion of the electrode tab material ca beremoved via laser cutting.

FIG. 2A shows a schematic of a device 200 to manufacture the fuse shownin FIGS. 1A-1B, according to embodiments. FIGS. 2B-2D illustrate amethod of manufacturing the fuse as shown in FIGS. 1A-1B, according toembodiments. The device 200 includes a punch 210 to make holes in metalsheets via punching. The device 200 also includes a top portion 220 anda bottom portion 230. A removable top die 225 is secured to the topportion 220 via M4 screws 222. Similarly, a removable cutting die 235 issecured to the bottom portion 230 via M4 screws 232.

The method to manufacture the fuses shown in FIG. 1A can include threesteps, shown in FIGS. 2B-2D, respectively. In FIG. 2B, a battery cell isprovided with at least one of the tabs positioned between the topportion 220 and the bottom portion 230 of the device 200. In FIG. 2C,the battery cell is secured to the device 200 by securing the topportion 220 of the device against the bottom portion 230 of the device200 (e.g., moving down the top portion 220 and/or moving up the bottomportion 230). In FIG. 2D, elongated holes (or other shapes of holes) aremade by pressing the punch 210 and fuses like those shown in FIGS. 1A-2Bcan be defined.

In FIGS. 2A-2D, the removable cutting die 235 includes two parallelcutting blades to make elongated holes. In some embodiments, theremovable cutting die 235 can be configured to make other shapes ofholes (e.g., round, elliptical, etc.) by changing the shape of thecutting blades.

FIG. 3 shows a schematic of an electrode tab 300 configured toelectrically couple an electrode to other components of anelectrochemical cell. In some embodiments, the electrode tab 300 caninclude a fuse region 315 defined by one or more apertures defined inthe electrode tab 300 by removing a portion or portions of electrode tabmaterial. The fused region 315 includes two bridges 312 a and 312 b toelectrically connect the top portion of the electrode tab 300 with thebottom portion of the tab 300. The total width of the two bridges 312 aand 312 b are smaller than the width of other parts of the electrode tab300. Therefore, upon overcharging, the two bridges 312 a and 312 b canpreferentially deform, break, melt, or otherwise discontinuecommunication of electrical charge through the electrode tab 300,thereby disconnecting the electrode tab 300 from the electrochemicalcell and protecting the electrode and/or electrochemical cell fromcatastrophic failure. In some embodiments, the electrode tab 300comprising a fuse region 315 is removably coupled to either the anode orcathode such that the electrode tab 300 can be replaced once the bridges312 a and 312 b deform, break, melt, or otherwise discontinuecommunication of electrical charge through the electrode tab 300 toprevent overcharging.

In some embodiments, the width of the bridges 312 a, 312 b can bedefined by the diameter of apertures formed in the electrode tab can beround, oblong, square, rectangular, triangular, or any other suitableshape. In some embodiments, the apertures formed in the electrode tabcan be centered within the electrode tab. In some embodiments, theapertures formed in the electrode tab can be positioned nearby to anedge of the electrode tab. In some embodiments, the apertures formed inthe electrode tab can be positioned such that a portion of one or moreedges of the electrode tab is removed.

In some embodiments, the width of each bridge 312 a or 312 b can beabout 100 μm to about 20 mm, about 500 μm to about 19 mm, about 750 μmto about 18 mm, about 0.5 mm to about 17 mm, about 1 mm to about 16 mm,about 1.5 mm to about 15 mm, about 2 mm to about 14 mm, about 3 mm toabout 13 mm, about 4 mm to about 12 mm, about 5 mm to about 11 mm, about6 mm to about 10 mm, about 7 mm to about 9 mm, about 0.5 mm to about 20mm, about 100 μm to about 19 mm, about 100 μm to about 18 μm, about 100μm to about 17 mm, about 100 μm to about 16 mm, about 100 μm to about 15mm, about 100 μm to about 14 mm, about 100 μm to about 13 mm, about 100μm to about 12 mm, about 100 μm to about 11 mm, about 100 μm to about 10mm, about 100 μm to about 9 mm, about 100 μm to about 8 mm, about 100 μmto about 7 mm, about 100 μm to about 6 mm, about 100 μm to about 5 mm,about 100 μm to about 4 mm, about 100 μm to about 3 mm, about 100 μm toabout 2 mm, about 100 μm to about 1 mm, about 100 μm to about 750 μm,about 100 μm to about 500 μm, about 500 μm to about 20 mm, about 750 μmto about 20 mm, about 0.5 mm to about 20 mm, about 1 mm to about 20 mm,about 2 mm to about 20 mm, about 3 mm to about 20 mm, about 4 mm toabout 20 mm, about 5 mm to about 20 mm, about 6 mm to about 20 mm, about7 mm to about 20 mm, about 8 mm to about 20 mm, about 9 mm to about 20mm, about 10 mm to about 20 mm, about 11 mm to about 20 mm, about 12 mmto about 20 mm, about 13 mm to about 20 mm, about 14 mm to about 20 mm,about 15 mm to about 20 mm, about 16 mm to about 20 mm, about 17 mm toabout 20 mm, about 18 mm to about 20 mm, or about 19 mm to about 20 mm,inclusive of all values and ranges therebetween. In some embodiments,the width of each bridge 312 a and 312 b can be greater than about 100μm, about 500 μm, about 750 μm, about 0.5 mm, about 1 mm, about 2 mm,about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 8 mm, about 9 mm,about 10 mm, about 11 mm, about 12 mm, about 13 mm, about 14 mm, about15 mm, about 16 mm, about 17 mm, about 18 mm, about 19 mm, or about 20mm, inclusive of all values and ranges therebetween. In someembodiments, the width of each bridge 312 a and 312 b can be less thanabout 20 mm, about 19 mm, about 18 mm, about 17 mm, about 16 mm, about15 mm, about 14 mm, about 13 mm, about 12 mm, about 11 mm, about 10 mm,about 9 mm, about 8 mm, about 7 mm, about 6 mm, about 5 mm, about 4 mm,about 3 mm, about 2 mm, about 1 mm, about 750 μm, about 500 μm, or about100 μm, inclusive of all values and ranges therebetween.

In some embodiments, the ratio of the width of each bridge 312 a or 312b to the width of the tab 300 can be about 1% to about 20% (e.g., about1%, about 2%, about 3%, about 4%, about 5%, about 7.5%, about 10%, about12.5%, about 15%, about 17.5%, or about 20%, including any values andsub ranges in between).

In some embodiments, the tab 300 can include more than two bridges 312 aand 312 b. For example, the tab 300 can include three bridges defined bytwo complete holes within the tab 300 and two half holes on each side ofthe tab 300. Other numbers of bridges are also possible.

FIG. 4 is a top view of electrode tabs including a fuse integral to theelectrode tab. The electrode tabs shown in FIG. 4 include two bridges,each of which has a width of about 1 mm. The electrode tabs shown inFIG. 4 include a plurality of apertures in each electrode tab having adiameter of about ⅛ inch. In some embodiments, the apertures formed inthe electrode tab can be round, oblong, square, rectangular, triangular,or any other suitable shape. In some embodiments, the apertures formedin the electrode tab can be centered within the electrode tab. In someembodiments, the apertures formed in the electrode tab can be positionednearby to an edge of the electrode tab. In some embodiments, theapertures formed in the electrode tab can be positioned such that aportion of one or more edges of the electrode tab is removed.

In some embodiments, two thinned portion of electrode tab material canbe formed when three apertures are defined in the electrode tab byremoving three portions of the electrode tab, as shown in FIG. 4. Insome embodiments, the thinned portion (bridges) can have a width definedby the distance between each aperture, the diameter of each aperture,and/or the width of the electrode tab. In some embodiments, the thinnedportion can be between about 100 μm to about 20 mm, about 500 μm toabout 19 mm, about 750 μm to about 18 mm, about 0.5 mm to about 17 mm,about 1 mm to about 16 mm, about 1.5 mm to about 15 mm, about 2 mm toabout 14 mm, about 3 mm to about 13 mm, about 4 mm to about 12 mm, about5 mm to about 11 mm, about 6 mm to about 10 mm, about 7 mm to about 9mm, about 0.5 mm to about 20 mm, about 100 μm to about 19 mm, about 100μm to about 18 μm, about 100 μm to about 17 mm, about 100 μm to about 16mm, about 100 μm to about 15 mm, about 100 μm to about 14 mm, about 100μm to about 13 mm, about 100 μm to about 12 mm, about 100 μm to about 11mm, about 100 μm to about 10 mm, about 100 μm to about 9 mm, about 100μm to about 8 mm, about 100 μm to about 7 mm, about 100 μm to about 6mm, about 100 μm to about 5 mm, about 100 μm to about 4 mm, about 100 μmto about 3 mm, about 100 μm to about 2 mm, about 100 μm to about 1 mm,about 100 μm to about 750 μm, about 100 μm to about 500 μm, about 500 μmto about 20 mm, about 750 μm to about 20 mm, about 0.5 mm to about 20mm, about 1 mm to about 20 mm, about 2 mm to about 20 mm, about 3 mm toabout 20 mm, about 4 mm to about 20 mm, about 5 mm to about 20 mm, about6 mm to about 20 mm, about 7 mm to about 20 mm, about 8 mm to about 20mm, about 9 mm to about 20 mm, about 10 mm to about 20 mm, about 11 mmto about 20 mm, about 12 mm to about 20 mm, about 13 mm to about 20 mm,about 14 mm to about 20 mm, about 15 mm to about 20 mm, about 16 mm toabout 20 mm, about 17 mm to about 20 mm, about 18 mm to about 20 mm, orabout 19 mm to about 20 mm, inclusive of all values and rangestherebetween. In some embodiments, the thinned portion can have a widthgreater than about 100 μm, about 500 μm, about 750 μm, about 0.5 mm,about 1 mm, about 2 mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm,about 8 mm, about 9 mm, about 10 mm, about 11 mm, about 12 mm, about 13mm, about 14 mm, about 15 mm, about 16 mm, about 17 mm, about 18 mm,about 19 mm, or about 20 mm, inclusive of all values and rangestherebetween. In some embodiments, the thinned portion can have a widthof less than about 20 mm, about 19 mm, about 18 mm, about 17 mm, about16 mm, about 15 mm, about 14 mm, about 13 mm, about 12 mm, about 11 mm,about 10 mm, about 9 mm, about 8 mm, about 7 mm, about 6 mm, about 5 mm,about 4 mm, about 3 mm, about 2 mm, about 1 mm, about 750 μm, about 500μm, or about 100 μm, inclusive of all values and ranges therebetween.

In some embodiments, the fuse can be made of any material typically usedfor anode or cathode terminals or tabs, such as aluminum, copper,nickel, zinc, any combination thereof. In some embodiments, the fuse isformed by removing material from the anode tab and/or the cathode tabusing the punch and die method described herein. In some embodiments, aplurality of fuses can be used to provide additional overchargeprotection to the battery cell. In some embodiments, where the fuse isformed by removing material from at least one of the anode tab and thecathode tab, the fuse is formed by punching a generally round hole inthe tab. In some embodiments, a plurality of holes can be punched in atleast one of the anode tab and the cathode tab, forming the fuse. Insome embodiments, the plurality of holes that are formed in the tab ortabs can be any number of holes (e.g., 2 holes, 3 holes, 4 holes, 5holes, 6 holes, 7 holes, 8 holes, 9 holes, 10 holes, 11 holes, 12 holes,13 holes, 14 holes, 15 holes, 16 holes, 17 holes, 18 holes, 19 holes, 20holes, etc.). In some embodiments, all of the holes are formed entirelywithin the tab or tabs. In other words, in some embodiments, no holesare formed in the tab that remove material from the outer edge of thetab or tabs. In some embodiments, at least one of the holes formed inthe tab or tabs is/are formed by removing material from the outer edgeof the tab or tabs.

FIG. 5 illustrates a method 10 for manufacturing an electrochemicalcell, the method including forming a plurality of current collectors,such as those described herein, a first current collector from theplurality of current collectors including an electrode tab, at 11.

The method 10 further includes electrically coupling each currentcollector of the plurality of current collectors to at least one otherof the plurality of current collectors such that a fuse is formedtherebetween, at 12. In some embodiments, the fuse can function duringnormal operation of the electrochemical cell such that multipleelectrode can be operated in parallel or in series, collectivelycomprising either the cathode or the anode. In some embodiments, thefuse can include any conductive material having a form factor andcompositional quality suitable such that the fuse breaks when at leastone of the current level, the voltage, and/or the temperature risesabove a predetermined current threshold, a predetermined voltagethreshold, and/or a predetermined temperature threshold, respectively.

The method 10 further includes disposing an electrode material (e.g., asemi-solid electrode material) onto a surface of each of the pluralityof current collectors, at 13. In some embodiments, the semi-solidelectrode material can include an active material and a conductivematerial in a liquid electrolyte. The semi-solid electrode material canbe any composition described herein, or any other suitable semi-solidelectrode material. In some embodiments, the semi-solid electrodematerial can include the active material and the liquid electrolytewithout necessarily including the conductive material. In someembodiments, the electrode material can be deposited onto at least aportion of a surface of each of the plurality of current collectors. Insome embodiments, the electrode material can be deposited onto at leasta portion of both surfaces of each of the plurality of currentcollectors. In some embodiments, the electrode material is not depositedonto the fuse material electrically coupling each of the currentcollectors together.

FIG. 6 illustrates an electrode 400 including a first current collector405 a, a second current collector 405 b, a third current collector 405c, and a fourth current collector 405 d (collectively, “currentcollectors 405”), such as those described herein, where the firstcurrent collector 405 a includes an electrode tab 420. As shown in FIG.6, the current collectors 405 are electrically coupled by way of a fuse425 a, 425 b, 425 c, each fuse configured to break to discontinuecurrent communication through the electrode tab 420 when a current levelor a voltage exceeds a predetermined current threshold or apredetermined voltage level, respectively. In some embodiments, at leastone of the current collectors 405 a, 405 b, 405 c, 405 d can beconfigured to communicate between about 1 mA/cm² to about 2,000 mA/cm²,about 5 mA/cm² to about 1,500 mA/cm², about 10 mA/cm² to about 1,000mA/cm², about 5 mA/cm² to about 1,000 mA/cm², or about 1 mA/cm² to about1,000 mA/cm², inclusive of all values and ranges therebetween. In someembodiments, the current collectors 405 a, 405 b, 405 c, 405 d can beconfigured to communicate current as described above with acorresponding increase in current collector temperature of less thanabout 50° C., about 40° C., about 30° C., about 20° C., about 10° C., orabout 5° C., inclusive of all values and ranges therebetween. In someembodiments, at least one of the fuses 425 a, 425 b, 425 c can beconfigured to be activated by between about 1 mAh/cm² and about 500mA/cm², about 5 mAh/cm² and about 400 mA/cm², about 10 mAh/cm² and about300 mA/cm², about 20 mAh/cm² and about 200 mA/cm², about 1 mAh/cm² andabout 450 mA/cm², about 1 mAh/cm² and about 400 mA/cm², about 1 mAh/cm²and about 350 mA/cm², about 1 mAh/cm² and about 300 mA/cm², about 1mAh/cm² and about 250 mA/cm², about 1 mAh/cm² and about 200 mA/cm²,about 1 mAh/cm² and about 150 mA/cm², about 1 mAh/cm² and about 100mA/cm², about 5 mAh/cm² and about 500 mA/cm², about 10 mAh/cm² and about500 mA/cm², about 20 mAh/cm² and about 500 mA/cm², about 50 mAh/cm² andabout 500 mA/cm², about 100 mAh/cm² and about 500 mA/cm², about 150mAh/cm² and about 500 mA/cm², about 200 mAh/cm² and about 500 mA/cm²,about 250 mAh/cm² and about 500 mA/cm², about 300 mAh/cm² and about 500mA/cm², about 350 mAh/cm² and about 500 mA/cm², about 400 mAh/cm² andabout 500 mA/cm², about 450 mAh/cm² and about 500 mA/cm², about 50mAh/cm² and about 500 mA/cm², about 50 mAh/cm² and about 500 mA/cm², Insome embodiments, the electrode 400 can be at least partially containedwithin a pouch material 440. In some embodiments, the electrode tab 420can extend beyond the pouch material 440. In some embodiments, thecurrent collectors 405 can be configured to fold, stack, be wound, orotherwise conform to a non-planar configuration.

In some embodiments, an electrode material can be disposed onto at leastone surface of each current collector 405, or onto both surfaces of eachcurrent collector 405. In some embodiments, the electrode material canbe a semi-solid electrode material, such as described herein.

In some embodiments, the pouch material 440 can be a first pouchmaterial and the current collectors 405 can be a first plurality ofcurrent collectors having a first electrode material disposed on atleast one of the surfaces of each of the first plurality of currentcollectors, collectively the “first electrode”. In some embodiments, anelectrochemical cell, such as a single pouch cell, can be formed byinterposing an ion-permeable membrane between the first electrode and asecond electrode, the second electrode including a second plurality ofcurrent collectors having a second electrode material disposed on afirst surface of each of the current collectors, and having a secondpouch material coupled to a second surface of each of the currentcollectors. In other words, the electrode shown in FIG. 6 can be acathode and can be paired with an anode having the same or similar formfactor and an ion-permeable membrane interposed therebetween, theresulting assembly being enclosed or substantially enclosed by pouchmaterial and stacked, folded, or wound to form the finishedelectrochemical cell. In some embodiments, when a fuse or multiple fusesis/are activated during abnormal electrochemical cell conditions, thepouch material, e.g., a laminate plastic pouch material, can melt orpartially melt to provide additional protection. In some embodiments,since the plurality of current collectors are electrically coupled viathe fuse material, a terminal electrode from among the plurality ofelectrodes can include an electrode tab while the remaining electrodesfrom the plurality of electrodes do not include an electrode tab. Inother words, since the remaining electrodes do not include a

FIG. 7 illustrates a method 20 for manufacturing an electrode, themethod including forming a deformable mesh from a polymer material, at21. In some embodiments, the polymer material can be selected such thatthe deformable mesh at least partially deforms, melts, disintegrates,breaks, or is otherwise affected by an increase in current level,voltage, temperature, or a combination thereof. The polymer material canbe any suitable polymer, plastic, rubber, synthetic rubber,silicone-containing, or bio-based material. By way of example only andwithout wishing to limit the scope of this disclosure in any way, thepolymer material can include polyethylene (PE), polypropylene (PP),polystyrene (PS), polyvinyl (PV), polyvinyl chloride (PVC), polymethylmethacrylate, intrinsically conducting polymers, stretch-orientedpolyacetylene, bioplastics, polyamides, polycarbonates, polyesters,high-density polyethylene, low-density polyethylene, polyethyleneterephthalate, polyurethanes, polyvinylidene chloride, acrylonitrilebutadiene styrene (ABS), polycarbonate/ABS, polyepoxide,polytetrafluoroethylene, phenolics, phenol formaldehyde, melamineformaldehyde, urea-formaldehyde, polyetheretherketone (PEEK),polyetherimide (PEI), plastarch, polylactic acid (PLA), polysulfone,silicone, furan, other suitable materials, and any combination thereof.

The method 20 further includes depositing a metal coating onto thedeformable mesh to form a deformable current collector, at 22. In someembodiments, a metal material, such as nickel, copper, aluminum, carbon,gold, or any other suitably conductive material based on the redoxchemistry described herein, can be coated onto the deformable mesh. Insome embodiments, the metal material can be mixed with a solvent orother liquid and spray onto the deformable mesh. In some embodiments,the deformable mesh can be electroplated with the metal material. Insome embodiments, the deformable mesh can be dip coated into a bathcontaining the metal material. In some embodiments, the metal materialcan be laminated onto the deformable mesh. In some embodiments, themetal material can be disposed onto the deformable mesh via chemicalvapor deposition (CVD) or similar methods. In some embodiments, themetal material can be disposed onto the deformable mesh via a spatteringprocess.

The method 20 further includes depositing a semi-solid electrodematerial onto the deformable current collector to form a semi-solidelectrode the semi-solid electrode material including an active materialand a conductive material in a liquid electrolyte, at 23. In someembodiments, at least a portion of the deformable current collector canextend beyond the deposited semi-solid electrode material to form anelectrode tab. In some embodiments, the semi-solid electrode materialcan be disposed onto only one side of the deformable current collector.In some embodiments, the semi-solid electrode material can be disposedonto both sides of the deformable current collector.

In some embodiments, the deformable current collector is configured todeform when a current level reaches or exceeds a predetermined currentthreshold. In some embodiments, the current collector is configured todeform when a voltage level reaches or exceeds a predetermined voltagethreshold. In some embodiments, the current collector is configured todeform when a temperature of the current collector reaches or exceeds apredetermined temperature threshold. Without wishing to be bound by anyparticular theory, when the deformable current collector is caused todeform, the deformable mesh material can deform (e.g., melt or partiallymelt), causing the metal coating thereon to deform also, which canreduce or discontinue completely the communication of electrical currentthrough the electrode tab.

In some embodiments, the electrode can be a cathode or an anode. In someembodiments, wherein the electrode is a cathode, the method 20 canfurther include interposing an ion-permeable membrane, such as thosedescribed herein, between the cathode and an anode to form anelectrochemical cell.

In some embodiments, an electrode can include more than one of theembodiments described herein. For example, in some embodiments, theelectrode can include the current collector manufactured byspray-coating a plastic mesh with a metal material and a portion of theelectrode tab can be removed according to any of the methods describedherein to form a fuse within the electrode tab. In some embodiments, theelectrode can include a plurality of current collectors electricallycoupled together using thin strips of electrically conductive materialconfigured to act as a fuse and a portion of the electrode tab can beremoved according to any of the methods described herein to form a fusewithin the electrode tab. In some embodiments, the electrode can includea plurality of current collectors electrically coupled together usingthin strips of electrically conductive material configured to act as afuse, the plurality of current collectors manufactured by spray-coatinga plastic mesh with a metal material, a portion of the electrode tabbeing removed according to any of the methods described herein to form afuse within the electrode tab.

FIGS. 8A-8D show a perspective view of an electrode at different stepsof the method 20 of FIG. 7. FIG. 8A illustrates a deformable meshmaterial, according to a particular form factor, however any suitableform factor can be chosen based on the desired form factor of thefinished electrode and/or electrochemical cell. In some embodiments, thedeformable mesh material can be stamped, cut, or otherwise manufacturedfrom a larger portion of deformable mesh material. In some embodiments,the deformable mesh can include or be a woven deformable material andcan be manufactured according to any suitable weaving process, extrudingprocess, or the like. As shown in FIGS. 8A-8D, the current collector caninclude an electrode tab. In some embodiments, the electrode tab can beformed simultaneously with the current collector according to the method20 or the like. In some embodiments, the electrode tab can be formed ata different time and coupled to the current collector or anothercomponent of the electrode at a later time.

In some embodiments, a metal coating can be disposed onto at least oneside of the deformable mesh, indicated as process A in FIG. 8B. WhileFIG. 8B illustrates a process, e.g., spray-deposition, whereby the metalcoating is applied from a distance, any suitable deposition process,such as those processes described above with regard to method 20 can beused to deposit the metal coating onto the deformable mesh. In someembodiments, after a time, such as a curing time, a cooling time, asolvent evaporation time, or another such time, the deformable currentcollector, as shown in FIG. 8C, is finished.

In some embodiments, as shown in FIG. 8D, an electrode material can bedisposed onto at least one surface of the deformable current collectorto form the finished electrode. The electrode material can be depositedonto at least one surface of the deformable current collector accordingto any suitable method, such as slurry casting, spray deposition,extrusion, drop casting, or the like. In some embodiments, the electrodematerial can include a semi-solid electrode material including an activematerial and a liquid electrolyte. In some embodiments, the semi-solidelectrode material can further include a conductive additive. In someembodiments, the electrode material can be deposited onto a main portionof the deformable current collector but not onto the electrode tab, asshown in FIG. 8D. In some embodiments, the electrode material can bedeposited onto both sides of the deformable current collector.

To provide an overall understanding, certain illustrative embodimentshave been described; however, it will be understood by one of ordinaryskill in the art that the systems, apparatuses, and methods describedherein can be adapted and modified to provide systems, apparatuses, andmethods for other suitable applications and that other additions andmodifications can be made without departing from the scope of thesystems, apparatuses, and methods described herein.

The embodiments described herein have been particularly shown anddescribed, but it will be understood that various changes in form anddetails may be made. Unless otherwise specified, the illustratedembodiments can be understood as providing exemplary features of varyingdetail of certain embodiments, and therefore, unless otherwisespecified, features, components, modules, and/or aspects of theillustrations can be otherwise combined, separated, interchanged, and/orrearranged without departing from the disclosed systems or methods.Additionally, the shapes and sizes of components are also exemplary andunless otherwise specified, can be altered without affecting the scopeof the disclosed and exemplary systems, apparatuses, or methods of thepresent disclosure.

Conventional terms in the field of electrochemical cells have been usedherein. The terms are known in the art and are provided only as anon-limiting example for convenience purposes. Accordingly, theinterpretation of the corresponding terms in the claims, unless statedotherwise, is not limited to any particular definition. Thus, the termsused in the claims should be given their broadest reasonableinterpretation.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement that is adapted to achieve the same purpose may besubstituted for the specific embodiments shown. Many adaptations will beapparent to those of ordinary skill in the art. Accordingly, thisapplication is intended to cover any adaptations or variations.

The above detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific embodiments that may bepracticed. These embodiments are also referred to herein as “examples.”Such examples may include elements in addition to those shown ordescribed. However, the present inventors also contemplate examples inwhich only those elements shown or described are provided. Moreover, thepresent inventors also contemplate examples using any combination orpermutation of those elements shown or described (or one or more aspectsthereof), either with respect to a particular example (or one or moreaspects thereof), or with respect to other examples (or one or moreaspects thereof) shown or described herein.

All publications, patents, and patent documents referred to in thisdocument are incorporated by reference herein in their entirety, asthough individually incorporated by reference. In the event ofinconsistent usages between this document and those documents soincorporated by reference, the usage in the incorporated reference(s)should be considered supplementary to that of this document; forirreconcilable inconsistencies, the usage in this document controls.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In this document, the terms “including” and “inwhich” are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, device,article, or process that includes elements in addition to those listedafter such a term in a claim are still deemed to fall within the scopeof that claim. Moreover, in the following claims, the terms “first,”“second,” and “third,” etc. are used merely as labels, and are notintended to impose numerical requirements on their objects.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) may be used in combination with each other. Otherembodiments may be used, such as by one of ordinary skill in the artupon reviewing the above description. The Abstract is provided to complywith 37 C.F.R. § 1.72(b), to allow the reader to quickly ascertain thenature of the technical disclosure and is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims.

In this Detailed Description, various features may have been groupedtogether to streamline the disclosure. This should not be interpreted asintending that an unclaimed disclosed feature is essential to any claim.Rather, inventive subject matter may lie in less than all features of aparticular disclosed embodiment. Thus, the following claims are herebyincorporated into the Detailed Description, with each claim standing onits own as a separate embodiment, and it is contemplated that suchembodiments may be combined with each other in various combinations orpermutations. The scope of the embodiments should be determined withreference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

1.-23. (canceled)
 24. An electrochemical cell, comprising: a cathodeincluding a cathode material disposed on a cathode current collector; ananode including an anode material disposed on an anode currentcollector; and an ion-permeable membrane interposed between the cathodeand the anode, wherein a component of at least one of the cathode andthe anode is configured to deform when a current level reaches orexceeds a predetermined current threshold.
 25. The electrochemical cellof claim 24, wherein the at least one of the cathode current collectorand the anode current collector includes a mesh comprising a polymermaterial.
 26. The electrochemical cell of claim 25, wherein the mesh isspray coated with a metal to form a porous current collector.
 27. Theelectrochemical cell of claim 26, wherein at least one of the cathodematerial and the anode material includes a mixture of a solid activematerial and a liquid electrolyte, the mixture being coated on theporous current collector.
 28. The electrochemical cell of claim 26,wherein at least a portion of the porous current collector extendsbeyond the ion-permeable membrane to form at least one of a cathode taband an anode tab.
 29. The electrochemical cell of claim 24, wherein thecathode current collector is a first current collector of a plurality ofcurrent collectors, the plurality of current collectors electricallycoupled together via a plurality of fuses, the first current collectorof the plurality of current collectors including an electrode tab,wherein the cathode material includes a mixture of a solid activematerial and a liquid electrolyte.
 30. The electrochemical cell of claim24, wherein the anode current collector is a first current collector ofa plurality of current collectors, the plurality of current collectorselectrically coupled together via a plurality of fuses, the firstcurrent collector of the plurality of current collectors including anelectrode tab, wherein the anode material includes a mixture of a solidactive material and a liquid electrolyte.
 31. The electrochemical cellof claim 25, wherein the mesh is configured to at least partiallydeform, melt, disintegrate, or break when the when a current levelreaches or exceeds a predetermined current threshold.
 32. Anelectrochemical cell, comprising: a cathode including a cathode materialdisposed on a cathode current collector; an anode including an anodematerial disposed on an anode current collector; and an ion-permeablemembrane interposed between the cathode and the anode, wherein at leastone of the anode current collector and the cathode current collectorincludes a deformable mesh material.
 33. The electrochemical cell ofclaim 32, wherein the deformable mesh material includes a polymermaterial.
 34. The electrochemical cell of claim 33, wherein thedeformable mesh material is coated with a metal to form a porous currentcollector.
 35. The electrochemical cell of claim 34, wherein at leastone of the cathode material and the anode material includes a mixture ofa solid active material and a liquid electrolyte, the mixture beingcoated on the porous current collector.
 36. The electrochemical cell ofclaim 34, wherein at least a portion of the porous current collectorextends beyond the ion-permeable membrane to form at least one of acathode tab and an anode tab.
 37. The electrochemical cell of claim 32,wherein the cathode current collector is a first current collector of aplurality of current collectors, the plurality of current collectorselectrically coupled together via a plurality of fuses, the firstcurrent collector of the plurality of current collectors including anelectrode tab, wherein the cathode material includes a mixture of asolid active material and a liquid electrolyte.
 38. The electrochemicalcell of claim 32, wherein the anode current collector is a first currentcollector of a plurality of current collectors, the plurality of currentcollectors electrically coupled together via a plurality of fuses, thefirst current collector of the plurality of current collectors includingan electrode tab, wherein the anode material includes a mixture of asolid active material and a liquid electrolyte.
 39. The electrochemicalcell of claim 32, wherein the deformable mesh material is configured tomelt, disintegrate, or break when the when a current level reaches orexceeds a predetermined current threshold.
 40. An electrochemical cell,comprising: a first electrode material disposed on a first currentcollector; a second electrode material disposed on a second currentcollector; and an ion-permeable membrane interposed between the firstelectrode material and the second electrode material, wherein at leastone of the first current collector and the second current collectorincludes a polymer mesh substrate coated with a metal.
 41. Theelectrochemical cell of claim 40, wherein the polymer mesh substrate isdeformable.
 42. The electrochemical cell of claim 40, wherein at leastone of the first electrode material and the second electrode materialincludes a mixture of a solid active material and a liquid electrolyte,the mixture being coated on the porous current collector.
 43. Theelectrochemical cell of claim 40, wherein at least a portion of theporous current collector extends beyond the ion-permeable membrane toform an electrode tab.
 44. The electrochemical cell of claim 40, whereinthe first current collector is electrically coupled to a plurality ofadditional current collectors via a plurality of fuses, the firstcurrent collector including an electrode tab, wherein the firstelectrode material includes a mixture of a solid active material and aliquid electrolyte.
 45. The electrochemical cell of claim 40, whereinthe second current collector is electrically coupled to a plurality ofadditional current collectors via a plurality of fuses, the secondcurrent collector including an electrode tab, wherein the secondelectrode material includes a mixture of a solid active material and aliquid electrolyte.
 46. The electrochemical cell of claim 40, whereinthe deformable mesh material is configured to melt, disintegrate, orbreak when the when a current level reaches or exceeds a predeterminedcurrent threshold.
 47. An electrode, comprising: a polymer meshsubstrate; a metal disposed on the polymer mesh substrate to form anelectrically conductive current collector; and an electrode materialdisposed on the current collector, wherein the polymer mesh substrate isconfigured to at least partially deform when a current level reaches orexceeds a predetermined current threshold during use of the electrode.48. The electrode of claim 47, wherein the electrically conductivecurrent collector is porous.
 49. The electrode of claim 48, wherein atleast a portion of the porous current collector extends beyond theion-permeable membrane to form an electrode tab.
 50. The electrode ofclaim 47, wherein the electrode material includes a mixture of a solidactive material and a liquid electrolyte, the mixture being coated onthe porous current collector.